Mining operations require the transport of highly abrasive particulate or slurry streams. The recovery of bitumen from oil sands is becoming increasingly important within the energy industry. Processing oil sand includes transporting and conditioning the oil sand as an aqueous slurry over kilometer lengths of pipe up to 1 meter in diameter. Processes for recovery of bitumen from oil sands are known (U.S. Pat. Nos. 4,255,433, 4,414,117, 4,512,956, 4,533,459, 5,039,227, 6,007,708, 6,096,192, 6,110,359, 6,277,269, 6,391,190, US2006/0016760, US2006/0249431, US2007/0023323, US2007/0025896, WO2006/060917, CA1251146, CA2195604, CA2227667, CA2420034, CA2445645, and CA2520943). Use of caustic to assist in the recovery process of oil from oil sands is also known (US2006/0016760 and US2006/0249431). Other mining operations that include the transport of highly abrasive particulate or slurry streams from the mine to processing refinery include, for example, iron ore, coal and coal dust, and the like, and in further non-mining transport processes, such as grain, sugar and the like.
Often, metal pipes, such as carbon steel or cast iron pipes, are used for the transport of these highly abrasive streams. They are expensive, heavy and only provide a temporary solution since they are eventually destroyed. To increase their lifetimes, the metal pipes may be rotated 90 degrees on their axes on a regular basis to provide a new transport surface. However, because of the pipe weight, this rotation is difficult and ultimately the entire pipe is worn out and must be replaced.
Use of plastic pipes, pipe liners and pipe coatings has been proposed to reduce these shortcomings. Material selection is critical. Many of the commonly available materials cannot stand up to such highly-abrasive mining streams and are quickly worn out. For example, high density poly(ethylene) pipes are generally used as liners for sanitary sewer and wastewater pipelines but they rapidly degrade under highly abrasive environments. U.S. Pat. No. 4,042,559 discloses abrasive granule-filled, partially-cured coatings for use in abrasion resistant coated pipes for the transport of mining slurries. U.S. Pat. No. 4,254,165 discloses processes to produce abrasion resistant pipes with 0.04-0.05-inch thick coatings of filled (such as sand) polyolefins, such as low and medium density poly(ethylene) and including poly(ethylene-co-acrylic acid). U.S. Pat. No. 4,339,506, WO90/10032, and CA1232553 disclose rubber liners for pipes. U.S. Pat. No. 4,215,178 discloses fluoropolymer-modified rubber pipe liners. US2006/0137757 and US2007/0141285 disclose fluoropolymer pipe liners. Polyurethane pipe coatings are known (U.S. Pat. No. 3,862,921, U.S. Pat. No. 4,025,670, US2005/0194718, US2008/0174110, GB2028461, JP02189379, JP03155937, and JP60197770). US2005/0189028 discloses metal pipe coated with a polyurethane liner to transport tar sand slurry. GB2028461 discloses an abrasion-resistant pipe lining comprising a urethane rubber thermoset embedded with the particles of the material to be transported (coal dust, grain or sugar) through transport of the materials during curing. Abrasion resistant pipes with elastomeric polyurea coatings are disclosed in U.S. Pat. No. 6,737,134. A shortcoming of the polyurethane coatings includes the highly complex processes for applying the coating to the metal pipe.
Use of grafted polyolefin compositions made from polyolefins grafted with an α-olefin monomer and α,β-ethylenically unsaturated carboxylic acid or anhydride as pipes, pipe liners and pipe coatings is known. For example, U.S. Pat. No. 4,481,239 discloses polyethylene powder coatings for pipes which may include an adhesive layer comprising certain acid copolymer powder coatings. U.S. Pat. Nos. 4,732,632, 5,178,902, 5,279,864, 6,224,710, 6,294,597, 6,976,510, US2005/0217747, US 005/0257848 and US2006/0108016 disclose corrosion and mechanical damage-resistant pipe coatings for pipe surfaces in which polyolefins with acrylate or maleic acid groups may be used as adhesives. U.S. Pat. No. 4,737,547 discloses films and pipes comprising blends which may include carboxylic acid- or maleic anhydride-grafted polyolefins.
U.S. Pat. Nos. 3,616,019, 3,619,320, 3,634,166 and 4,232,086 disclose the use of carboxyl-modified polyolefins as adhesives for polymeric metal coatings. U.S. Pat. Nos. 3,932,368, 4,237,037, 4,345,004 and 4,910,046 disclose polyolefin powder coatings for metal substrates which may include polar group modified olefinic resins, such as carboxyl- or anhydride-modified resins. U.S. Pat. Nos. 4,048,355, 4,049,904, 4,092,452 and 4,824,736 disclose a metal coating of a modified polyolefin grafted with a carboxylic acid or anhydride. U.S. Pat. No. 5,091,260 discloses a corrosion-resistant coating for metal substrates comprising 30-99 wt % metallic zinc and a carboxylic acid-grafted polyolefin. U.S. Pat. No. 5,211,990 disclose a flame spraying process of polyolefin powders onto metal substrates that include polyolefins grafted with acid or anhydride functionality and ethylene/(meth)acrylic acid copolymers and ionomers derived therefrom. U.S. Pat. No. 5,275,848 discloses a powder coating process for metal substrates with polyolefin powders that include polyolefins grafted with acid or anhydride functionality and ethylene/(meth)acrylic acid copolymers and ionomers derived therefrom. U.S. Pat. No. 5,677,377 and U.S. Pat. No. 5,677,378 disclose corrosion-resistant powder coatings for steel plate which include maleic anhydride-grafted polypropylene powder. U.S. Pat. No. 5,976,652 discloses corrosion-resistant polypropylene film coatings for steel containers adhered with carboxylic acid- or anhydride-functional polypropylenes.
A shortcoming of grafted polyolefin pipes, pipe liners and coatings in the art is low abrasion resistance resulting in short service lifetimes.